Making future space exploration less costly is the ultimate goal of a group of engineering students at UC San Diego who have created a working metal rocket engine from a 3-D printer.

Ten students spent about eight months designing and analyzing the 7-inch-long engine, which they tested in the Mojave Desert in early October.

Much to their delight, it worked.

“We did a countdown from 10 to one, and at five, I hit the igniter button. And when it hit one, I opened both of the valves” releasing fuel and liquid oxygen, recalled Deepak Atyam, a 20-year-old junior.

“At that instant, we were able to see fire that came out and our combustion actually working properly.”

Even though the group stood behind a bunker about 40 yards away, they still felt a burst of heat as the engine roared to life. It was a static test, meaning the rocket fired but didn’t go anywhere.

After realizing what they did, the group cheered.

“When we did the test, people were in shock, primarily because it was working,” Atyam said, the founding president of the university’s chapter of Students for the Exploration and Development of Space.

They weren’t the only ones with doubts.

UC San Diego professor Forman Williams, an expert in combustion research who advises the group, admitted he wasn’t sure they’d be able to create a working engine using 3-D printing technology. The process creates a three-dimensional solid object from a digital model, building successive layers of material into the shapes called for in the design. In this case, the engine was made from cobalt-chromium.

“These things are very intricate to design and very prone to combustion instability. They require a very fine tolerance,” he said. “They were able to design it and test it successfully with this 3-D printing approach, which is kind of amazing.”

Williams, who is on sabbatical in Spain, said in a telephone interview that the project was completely the work of the undergraduates — and that he only answered occasional questions.

“It was totally student generated. These kids got the ideas by themselves and did the designs by themselves,” Williams said.

The project was built with the assistance of NASA’s Marshall Space Flight Center, which contributed $5,000 to have the design printed by GPI Prototype and Manufacturing Services in Illinois. Students raised about $1,800 and relied on donated equipment and materials from several sponsors to design and build the test system.

The group was advised by several mentors, including Solana Beach engineer Paul Breed, Jonathan Jones at NASA’s Marshall Space Flight Center and Carl Tedesco at Flometrics in Carlsbad.

The successful test means UC San Diego is the first university to make a 3-D print rocket engine and test it. Four other entities, including two NASA centers, have manufactured and tested similar engines.

From a practical point of view, Atyam said students hope their work could make the launches of miniature satellites — known as CubeSats — more affordable.

The ultimate goal, he said, is to make it so a company could “basically stamp these engines out and send them out to companies whenever they need them.”

Atyam said the team worked 15 hours a week at times on the project, eager to apply the theoretical lessons they were learning in the classroom to a hands-on project. The test proved the engine was accurate enough to be able to hold the temperatures and pressures that were needed.

The project didn’t come off without some glitches, though.

The engine was supposed to be in one piece, but arrived in two. After further testing, students realized that little holes in the injector plate were far smaller than the design called for — so small they provided no way to cool the combustion chamber of the motor.

While working a summer internship at the NASA Langley Research Center in Virginia, Atyam got help in redrilling the holes and welding the pieces together.

As for the future, Atyam said the team likely will expand to 20 students for its next project — building a larger engine and a rocket to launch it. “I think this technique can be the future of what we move to in the aerospace field to send payloads into orbit,” he said.